Any non-SSD hard drives get Sata 3 speeds?

Are there any non-SSD hard drives whose speed gets close to taking advantage of sata 3?

I ask because I am looking to buy a secondary 1 TB (non-SSD) hard drive for my new computer that will be arriving soon. The primary hard drive is an SSD. I have sata 2 and sata 3 ports to hook this new hard drive into, but if I'm not going to get close to sata 3 speeds I might as well stick with a sata 2 cable and sata 2 port.

References, benchmarks, experience, etc. are welcome!

Marc

Posted 2012-10-08T23:09:44.540

Reputation: 13

Purchasing and product recommendations are really not within the scope of any of the SE sites, so this isn't the right place to ask. You can check our list of places where you can ask questions that are not SuperUser questions. – Der Hochstapler – 2012-10-08T23:31:48.143

Answers

If a drive can service the request from its onboard DRAM cache, that transfer could happen at SATA 3 speeds. However, the overwhelming majority of the drive's transfers will be to or from the platters. Current sequential transfer rates top out at under 200 MB/s, never mind random I/O.

So as a practical matter, it really doesn't matter which sata port you plug a regular hard drive into.

afrazier

Posted 2012-10-08T23:09:44.540

Reputation: 21 316

Interesting. I've noticed quite a few regular hard drives that are Sata 3, and seem to have a little more cache. The price points are about the same.

At this point I'm leaning towards purchasing a SATA 3 with 64MB cache and SATA 3 cable (and plug into SATA 3 port) and hope that I get lucky with the caching (depending on what I'm doing). – Marc – 2012-10-08T23:29:03.263

1"onboard DRAM cache" - actually the memory is probably SRAM, not DRAM. Data "from the platters" is always buffered, and not released by the on-board controller until the entire sector is read and validated. So data transferred out of the sector buffer uses full SATA speed just like the data from cache. There's widespread misunderstanding of idle time on the SATA bus and actual data rate versus averaged throughput. Probably the only people who really understand this stuff are those who actually work (or have worked as I have) with HDD internals. – sawdust – 2012-10-09T01:39:31.820

No.

SATA-2 is good for transfers speeds up to 270MB per second. (Reference: Lots of SSD benchmarks on several sites where they used a SSD which is faster, but gets limited to these speeds when used on a SATA-2 interface). This actually varies per chipset and drive, but 270MB/sec seems to be a good value for SATA-2.

If you are curious read Toms hardware, Anandtech and lots of similar sites.

Conventional hard drives however are in the order of 100 MB/sec. A long way from that 270MB/sec. Even if you get a 15K RPM drive and do nothing but sequential reads then the speed of a single drive will be around 200 MB/sec. Still shy from 270. (Reference: Manufacturers claimed speeds for 15K RPM SAS drives.)

Hennes

Posted 2012-10-08T23:09:44.540

Reputation: 60 739